1. Field of the Invention
The present invention relates to a voice controllable elevator system which operates by commands given in voices, instead of usual manual commands, and more particularly, to a command input device for such a voice controlled elevator which allows inputs of commands in terms of voices.
2. Description of the Background Art
A usual conventional elevator system found in various buildings is normally operated by a user manually. The manual control operations to be performed by a user include:
(1) pressing of a elevator call button at a hallway,
(2) pressing of a destination call button in an elevator car, and
(3) pressing of a door open/close button in an elevator car, in response to which the elevator carries out the specified functions.
Now, the various control buttons provided in such a conventional elevator system are not necessarily convenient for some situations. For instance, for a user carrying some objects by both hands, it is often necessary to put these objects on a floor first, and then press the correct button to control the elevator, which is a rather cumbersome procedure. Also, for a blind person, it is a very cumbersome task to find tiny buttons. Another awkward situation is a case in which someone else is standing in front of the control buttons.
As a solution to such inconveniences associated with a conventional elevator system, a voice controllable elevator system which can be operated by commands given in voices instead of usual manual commands has been proposed.
In such a voice controllable elevator system, a microphone for receiving commands given in voices is provided in a hallway, in place of a usual elevator call button, and a speech recognition process is carried out for the voices collected by this microphone, such that the commands given in voices are recognized and the elevator system is operated in accordance with the recognized commands. For instance, when a user said "fifth floor", this command is recognized, and in response to this command a call response lamp for the fifth floor is lit and the elevator moves to the fifth floor, just as if the destination call button for the fifth floor is manually operated in a usual conventional elevator system.
The speech recognition process utilizes a number of words registered in advance in a form of a dictionary, so that the input speech is frequency analyzed first and then the result of this frequency analysis is compared with registered word data in the dictionary, where the words are considered as being recognized when a similarity between the result of the frequency analysis and the most closely resembling word of the registered word data is greater than a certain threshold level. For such a speech recognition process, a type of speech recognition technique called non-specific speaker word recognition is commonly employed, in which a speaker of the speech to be recognized is not predetermined. The recognition is achieved in units of individual words, such as "open", "close", "door", "fifth", "floor", etc.
Now, such a voice controllable elevator system is associated with a problem of reduced recognition rate, due to the fact that the dictionary is normally prepared at a quite noiseless location at which over 90% of recognition rate may be obtainable. An actual location of the elevator system is much noisier.
To cope with this problem, it is custom to set up a threshold loudness level for the command inputs, such that the recognition is not effectuated unless the loudness of the voice input reaches this threshold loudness level, in hope of distinguishing actual commands and other noises at a practical level.
FIG. 1 shows an example of a command input device for such a conventional voice controllable elevator system, located at an elevator hallway. In FIG. 1, a elevator location indicator 102, elevator call buttons 103, and a microphone 104 are arranged in a vicinity of an elevator door 101. When a user gives some commands in voice toward this microphone 104, the commands are recognized and the elevator system is operated in accordance with the recognized commands.
However, even with over 90% recognition rate, there is a considerable chance for wasteful and undesirable false functioning of the elevator system due to false speech recognition, compared to a conventional manually controllable elevator system. Also, when a user gives a command in a form not registered in the dictionary, such as "shut the door", "let me in", and "let me out", the elevator system is non-responsive.
Moreover, in a so called group administration elevator system in which a plurality of elevators are administered as a group such that whenever an elevator call is issued, a most convenient one of these elevators is selected and reserved for this call immediately, the false functioning of the elevator system due to one false shape recognition from one user may causes disturbances to other users.